1. Field of the Invention
The present invention relates to a television signal receiving apparatus for receiving a new standard television signal in an environment in which both a broadcasting wave of the new standard television signal and a broadcasting wave of the conventional standard television signal exist.
2. Description of the Prior Art
The current color television systems for the terrestrial broadcasting are the NTSC system, the PAL system and the SECAM system. On the other hands, various new standard high definition television (HDTV) systems for satellite broadcasting and terrestrial broadcasting have been proposed and under development. In Japan and the U.S., the frequency bands allocated for the terrestrial television broadcasting are almost occupied by the channels of the current NTSC system. Accordingly, it is difficult to allocate adequate frequency band for the new standard broadcasting as far as the conventional standard broadcasting exists. So, to realize the new standard broadcasting in the environment in which the conventional standard broadcasting exists, it would be necessary to allocate the channels which are allocated for the conventional broadcasting also for the new standard broadcasting in different service areas. That is, a channel which is not used for the conventional broadcasting in an area (now, adjacent channels are not used in one area so as to avoid intermodulated interferences) may be allocated for the new standard broadcasting in the area. In this case, it is necessary to make the transmitting power of the new standard broadcasting to be small so as not to cause interference in a conventional standard broadcasting signal of the same channel which is broadcasted in, for example, an adjacent area.
In this case, however, there arises an issue of difficulty for a television receiver which is designed for receiving the new standard broadcasting signal to adequately receive the new standard broadcasting wave which has a small power under presence of the conventional broadcasting wave.